HP 8340A Service Manual page 38

Going from left to right, the first three octal digits are determined by bit numbers 9 through 15.
The fourth octal digit is determined by bits 6 through 8 and since bits 6 and 7 are "don't care"
terms, the fourth digit can range from 0 through 3. The last two octal digits are labeled as "don't
care" terms because bits 0 through 5 are "don't care" terms. If one of the above octal numbers
did not match the octal number in.the ENTRY DISPLAY, then A59U18 would be defective.
If A59U18 passed the above test, the + 5V and ground connections to the inputs of A59U18
would be reversed. The connections would be as follows:
Input Pin
Voltage
Binary Value
The following table would be constructed:
Bit Number 1 5
Binary Value 0
The binary number above is converted to an octal number. The possible octal numbers are as
follows:
If one of the above octal numbers did .not match the octal number in the ENTRY DISPLAY,
then A59U18 would be defective. If both the previous test and this one passed, then the
operation of A59Ul8 would be verified.
Model 8340A - Service
8 13 2
0 + 5 0
1 0
0
1 4 13 12 11 10 9
1 0 1 0 1 0
0524xx
0525xx
0526xx
0527xx
Scans by HB9HCA and HB9FSX
11 6 15 17
+ 5 0 + 5
1 0 1
8 7 6 5 4 3
1
x x x
x x
4
+ 5
0
0 1
2 1 0
x x x
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